The present invention relates to apparatus for controlling the flow of particulate material. More particularly, the present invention relates to apparatus which allows the vertical flow of tablets or capsules through a tube or other vessel to be controlled without breaking the tablets or crushing the capsules.
Previous apparatus for use in filling containers so as to protect the particulate material being filled are described in the following U.S. Pat. Nos.: 2,590,215 to Sausa; 2,598,207 to Bailey et al.; 2,604,246 to Hood; 2,716,575 to Vickers; 3,260,285 to Vogt; 3,415,485 to Hirs et al.; and 4,785,841 to Breckner.
By the present invention, there is provided an improved device which functions as a tablet or a capsule drop tube assembly so as to control and provide for a gentle downward flow of tablets or capsules through a tube or other vessel without breaking the tablets or crushing the capsules. The present invention employs a double tube arrangement, including a flexible tube which is of a uniform or consistent thickness throughout its length and is employed to control the flow of tablets by restricting flow along the vertical length of the tube or by completely closing off the flow.
The flow of tablets or capsules is controlled by introducing air under pressure between a pair of vertical tubes, including an outer tube and a soft, flexible inner tube. This introduction of air causes the inner tube to collapse and thus restrict flow along the passageway interior of the tube. The degree of flow restriction is determined by the amount of air which is introduced or exhausted. Because the inner liner is soft and flexible, the control device does not break the tablets or crush the capsules. The soft, flexible inner tube employed in the present invention can be of any reasonable length, thus allowing the flow to be controlled over a considerable length or area rather than at just a single point.